The present invention is directed to nucleic acid sequences that control the expression of genes in eukaryotic cells. More particularly, the invention is directed to a gene promoter that confers a high level of expression to genes that are operably linked to the promoter.
The present invention relates to a novel regulatory element which confers a high level of expression in plant cells to genes that are operably linked to the regulatory element. The ability to control the level of gene expression in plants is important for many applications of genetic transformation procedures including those directed to crop improvement.
In eukaryotic organisms, multi-level regulatory systems exist to control gene expression. The transcription process is an integral part of such systems and is involved in synthesis of mRNA molecules. The efficiency of transcription is mostly determined by a region of DNA called the promoter. The promoter consists of gene sequences upstream of the site of transcription initiation. The components of the promoter region include the xe2x80x9cTATAxe2x80x9d box and often a xe2x80x9cCAATxe2x80x9d box. In addition, many other regulatory elements that affect transcription may be present in the promoter sequences. The coordinated action of cellular proteins (transcription factors) interacting with promoter sequences determines the specificity of a particular promoter and its effectiveness. Since most eukaryotic genes are stringently regulated, there is a limited availability of promoters with constitutive, strong expression.
The present invention describes the isolation and purification of a DNA sequence that expresses operably linked genes to high levels in plant cells. The promoter sequence described in the present invention expresses genes at a level equal to or higher than that obtained from one of the strongest presently available promoters xe2x80x94the 35S cauliflower mosaic virus promoter. Such promoters are needed to direct a high level of protein expression in transgenic plants. The strong promoter of the resent invention is used to construct expression vectors for expressing genes in plant cells. In one embodiment, a plant expression vector is provided that comprises the regulatory element of SEQ ID NO: 2 operably linked to a non-natively associated gene, and this vector is used to produce transgenic plants.